(Preface of A Contribution to the Critique of
Political Economy, Reader, pp. 4-5, http://www.marxists.org/archive/marx/works/1859/critique-pol-economy/preface-abs.htm

In the social production of their
life, men enter into definite relations that are indispensable and
independent of their will, relations of production which correspond to a
definite stage of development of their material productive forces. The sum
total of these relations of production constitutes the economic structure
of society, the real foundation, on which rises a legal and political
superstructure and to which correspond definite forms of social
consciousness...

At a certain stage of their
development, the material productive forces of society come in conflict
with the existing relations of production, or — what is but a legal
expression for the same thing — with the property relations within which
they have been at work hitherto. From forms of development of the
productive forces these relations turn into their fetters.

Then begins an epoch of social
revolution. With the change of the economic foundation the entire immense
superstructure is more or less rapidly transformed. In considering such
transformations a distinction should always be made between the material
transformation of the economic conditions of production, which can be
determined with the precision of natural science, and the legal,
political, religious, aesthetic or philosophic — in short, ideological
forms in which men become conscious of this conflict and fight it out.

The serf belongs to the soil, and
to the lord of the soil he brings its fruit. The free laborer, on the
other hand, sells his very self, and that by fractions. He auctions off
eight, 10, 12, 15 hours of his life, one day like the next, to the highest
bidder, to the owner of raw materials, tools, and the means of life --
i.e., to the capitalist. The laborer belongs neither to an owner nor to
the soil, but eight, 10, 12, 15 hours of his daily life belong to
whomsoever buys them... The worker, whose only source of income is
the sale of his labor-power, cannot leave the whole class of buyers, i.e.,
the capitalist class, unless he gives up his own existence. He does not
belong to this or that capitalist, but to the capitalist class; and it is
for him to find his man -- i.e., to find a buyer in this capitalist class.

B. Stereotype of Capitalist(Capital, "Preface to the First German Edition," Reader, p. 297,
http://csf.colorado.edu/mirrors/marxists.org/archive/marx/works/1867-c1/p1.htm)

To prevent possible
misunderstanding, a word. I paint the capitalist and the landlord in no
sense couleur de rose. But here individuals are dealt with only in so far
as they are the personifications of economic categories, embodiments of
particular class-relations and class-interests. My standpoint, from which
the evolution of the economic formation of society is viewed as a process
of natural history, can less than any other make the individual
responsible for relations whose creature he socially remains, however much
he may subjectively raise himself above them.

Except as personified capital, the
capitalist has no historical value… But, so far as he is personified
capital, it is not values in use and the enjoyment of them, but
exchange-value and its augmentation, that spur him into action.
Fanatically bent on making value expand itself, he ruthlessly forces the
human race to produce for production's sake; he thus forces the
development of the productive powers of society, and creates those
material conditions, which alone can form the real basis of a higher form
of society, a society in which the full and free development of every
individual forms the ruling principle... He shares with the miser the passion for
wealth as wealth. But that which in the miser is a mere idiosyncrasy, is,
in the capitalist, the effect of the social mechanism, of which he is but
one of the wheels. Moreover, the development of capitalist production
makes it constantly necessary to keep increasing the amount of the capital
laid out in a given industrial undertaking, and competition makes the
immanent laws of capitalist production to be felt by each individual
capitalist, as external coercive laws. It compels him to keep constantly
extending his capital, in order to preserve it, but extend it he cannot,
except by means of progressive accumulation.

The average price of wage labor is
the minimum wage, i.e., that quantum of the means of subsistence which is
absolutely requisite to keep the laborer in bare existence as a laborer.
What, therefore, the wage laborer appropriates by means of his labor
merely suffices to prolong and reproduce a bare existence. . . . an
appropriation that is made for the maintenance and reproduction of human
life, and that leaves no surplus wherewith to command the labor of others.

[I]t appears that the capitalist
buys their labor with money, and that for money they sell him their labor.
But this is merely an illusion. What they actually sell to the capitalist
for money is their labor-power. This labor-power the capitalist buys for a
day, a week, a month, etc. And after he has bought it, he uses it up by
letting the worker labor during the stipulated time. With the same amount
of money with which the capitalist has bought their labor-power (for
example, with two shillings) he could have bought a certain amount of
sugar or of any other commodity… Labor-power, then, is a commodity, no
more, no less so than is the sugar. The first is measured by the clock,
the other by the scales.

2. The Value of Labor Power(Wage Labour and Capital, in Reader, p. 206,http://csf.colorado.edu/mirrors/marxists.org/archive/marx/works/1840/wage-lab/ch04.htm)

Now, the same general laws which
regulate the price of commodities in general, naturally regulate wages, or
the price of labor-power... The fluctuations of wages correspond to the
fluctuation in the price of commodities in general. But within the limits
of these fluctuations the price of labor-power will be determined by the
cost of production, by the labor-time necessary for production of this
commodity: labor-power.

What, then, is the cost of
production of labor-power?

It is the cost required for the
maintenance of the laborer as a laborer, and for his education and
training as a laborer.

Therefore, the shorter the time
required for training up to a particular sort of work, the smaller is the
cost of production of the worker, the lower is the price of his
labor-power, his wages. In those branches of industry in which hardly any
period of apprenticeship is necessary and the mere bodily existence of the
worker is sufficient, the cost of his production is limited almost
exclusively to the commodities necessary for keeping him in working
condition. The price of his work will therefore be determined by the price
of the necessary means of subsistence.

The value of labour-power is
determined, as in the case of every other commodity, by the labour-time
necessary for the production, and consequently also the reproduction, of
this special article. . . For his maintenance he requires a given quantity
of the means of subsistence. Therefore the labour-time requisite for the
production of labour-power reduces itself to that necessary for the
production of those means of subsistence; in other words, the value of
labour-power is the value of the means of subsistence necessary for the
maintenance of the labourer...

His means of subsistence must therefore
be sufficient to maintain him in his normal state as a labouring
individual. His natural wants, such as food, clothing, fuel, and housing,
vary according to the climatic and other physical conditions of his
country. On the other hand, the number and extent of his so-called
necessary wants, as also the modes of satisfying them, are themselves the
product of historical development, and depend therefore to a great extent
on the degree of civilization of a country, more particularly on the
conditions under which, and consequently on the habits and degree of
comfort in which, the class of free labourers has been formed. In
contradistinction therefore to the case of other commodities, there enters
into the determination of the value of labour-power a historical and moral
element. Nevertheless, in a given country, at a given period, the average
quantity of the means of subsistence necessary for the labourer is
practically known.

The owner of labour-power is
mortal. If then his appearance in the market is to be continuous, … the
seller of labour-power must perpetuate himself… Hence the sum of the means
of subsistence necessary for the production of labour-power must include
the means necessary for the labourer's substitutes, i.e., his children, in
order that this race of peculiar commodity-owners may perpetuate its
appearance in the market.

In order to modify the human
organism, so that it may acquire skill and handiness in a given branch of
industry, and become labour-power of a special kind, a special education
or training is requisite, and this, on its part, costs an equivalent in
commodities of a greater or less amount. This amount varies according to
the more or less complicated character of the labour-power. The expenses
of this education (excessively small in the case of ordinary labour-power),
enter pro tanto into the total value spent in its production.

E. If everything is sold at its
value, what is the origin of profits
(or surplus value)?(Capital, vol I, Chapter 5 http://csf.colorado.edu/mirrors/marxists.org/archive/marx/works/1867-c1/ch05.htm)

The creation of surplus-value, and
therefore the conversion of money into capital, can . . . be explained
neither on the assumption that commodities are sold above their value, nor
that they are bought below their value. . .

The conversion of money into
capital has to be explained on the basis of the laws that regulate the
exchange of commodities, in such a way that the starting-point is the
exchange of equivalents. Our friend, Moneybags… must buy his commodities
at their value, must sell them at their value, and yet at the end of the
process must withdraw more value from circulation than he threw into it at
starting. . . These are the conditions of the problem.

We assumed, on the occasion of its
sale, that the value of a day's labour-power is three shillings, and that
six hours' labour is incorporated in that sum; and consequently that this
amount of labour is requisite to produce the necessaries of life daily
required on an average by the labourer. If now our spinner by working for
one hour, can convert 1 2/3 lbs. of cotton into 1 2/3 lbs. of yarn, it
follows that in six hours he will convert 10 lbs. of cotton into 10 lbs.
of yarn. Hence, during the spinning process, the cotton absorbs six hours'
labour. The same quantity of labour is also embodied in a piece of gold of
the value of three shillings. Consequently by the mere labour of spinning,
a value of three shillings is added to the cotton. . .

Our capitalist stares in
astonishment. The value of the product is exactly equaI to the value of
the capital advanced. The value so advanced has not expanded, no
surplus-value has been created, and consequently money has not been
converted into capital. . .

Our capitalist, who is at home in
his vulgar economy, exclaims: "Oh! but I advanced my money for the express
purpose of making more money." . . . He threatens all sorts of things. He
won't be caught napping again. . . . He tries persuasion. "Consider my
abstinence; I might have played ducks and drakes with the 15 shillings;
but instead of that I consumed it productively, and made yarn with it." .
. . He now gets obstinate. "Can the labourer," he asks, "merely with his
arms and legs, produce commodities out of nothing? Did I not supply him
with the materials, by means of which, and in which alone, his labour
could be embodied?.. The capitalist paid to the labourer a value of 3
shillings, and the labourer gave him back an exact equivalent in the value
of 3 shillings, added by him to the cotton: he gave him value for value.
Our friend, up to this time so purse-proud, suddenly assumes the modest
demeanour of his own workman, and exclaims: "Have I myself not worked?
Have I not performed the labour of superintendence and of overlooking the
spinner? And does not this labour, too, create value?" His overlooker and
his manager try to hide their smiles. Meanwhile, after a hearty laugh, he
re-assumes his usual mien. Though he chanted to us the whole creed of the
economists, in reality, he says, he would not give a brass farthing for
it. He leaves this and all such like subterfuges and juggling tricks to
the professors of Political Economy, who are paid for it. He himself is a
practical man; and though he does not always consider what he says outside
his business, yet in his business he knows what he is about.

Let us examine the matter more
closely. The value of a day's labour-power amounts to 3 shillings, because
on our assumption half a day's labour is embodied in that quantity of
labour-power, i.e., because the means of subsistence that are daily
required for the production of labour-power, cost half a day's labour. But
the past labour that is embodied in the labour-power, and the living
labour that it can call into action; the daily cost of maintaining it, and
its daily expenditure in work, are two totally different things. The
former determines the exchange-value of the labour-power, the latter is
its use-value. The fact that half a day's labour is necessary to keep the
labourer alive during 24 hours, does not in any way prevent him from
working a whole day. Therefore, the value of labour-power, and the value
which that labour-power creates in the labour-process, are two entirely
different magnitudes; and this difference of the two values was what the
capitalist had in view, when he was purchasing the labour-power. . . What
really influenced him was the specific use-value which this commodity
possesses of being a source not only of value, but of more value than it
has itself. . .

Our capitalist foresaw this state
of things, and that was the cause of his laughter. The labourer therefore
finds, in the workshop, the means of production necessary for working, not
only during six, but during twelve hours. . . The trick has at last
succeeded; money has been converted into capital. . .

Every condition of the problem is
satisfied, while the laws that regulate the exchange of commodities, have
been in no way violated. Equivalent has been exchanged for equivalent. . .

The one capitalist can drive the
other from the field and carry off his capital only by selling more
cheaply. . .

. . . And so there arises among the
capitalists a universal rivalry for the increase of the division of labor
and of machinery and for their exploitation upon the greatest possible
scale.

If, now, by a greater division of
labor, by the application and improvement of new machines, by a more
advantageous exploitation of the forces of nature on a larger scale, a
capitalist has found the means of producing with the same amount of labor
(whether it be direct or accumulated labor) a larger amount of products of
commodities than his competitors -- if, for instance, he can produce a
whole yard of linen in the same labor-time in which his competitors weave
half-a-yard -- how will this capitalist act? . . .

But the privilege of our capitalist
is not of long duration. Other competing capitalists introduce the same
machines, the same division of labor, and introduce them upon the same or
even upon a greater scale. And finally this introduction becomes so
universal that the price of the linen is lowered not only below its old,
but even below its new cost of production.

The capitalists therefore find
themselves, in their mutual relations, in the same situation in which they
were before the introduction of the new means of production; and if they
are by these means enabled to offer double the product at the old price,
they are now forced to furnish double the product for less than the old
price. Having arrived at the new point, the new cost of production, the
battle for supremacy in the market has to be fought out anew. Given more
division of labor and more machinery, and there results a greater scale
upon which division of labor and machinery are exploited. And competition
again brings the same reaction against this result.

But what effect do these
conditions, which are inseparable from the growth of productive capital,
have upon the determination of wages?

The greater division of labor
enables one laborer to accomplish the work of five, 10, or 20 laborers; it
therefore increases competition among the laborers fivefold, tenfold, or
twentyfold. The laborers compete not only by selling themselves one
cheaper than the other, but also by one doing the work of five, 10, or 20;
and they are forced to compete in this manner by the division of labor,
which is introduced and steadily improved by capital.

Furthermore, to the same degree in
which the division of labor increases, is the labor simplified. The
special skill of the laborer becomes worthless. He becomes transformed
into a simple monotonous force of production, with neither physical nor
mental elasticity. His work becomes accessible to all; therefore
competitors press upon him from all sides. Moreover, it must be remembered
that the more simple, the more easily learned the work is, so much the
less is its cost to production, the expense of its acquisition, nd so much
the lower must the wages sink -- for, like the price of any other
commodity, they are determined by the cost of production. Therefore, in
the same manner in which labor becomes more unsatisfactory, more
repulsive, do competition increase and wages decrease.

As soon as this process of
transformation has sufficiently decomposed the old society from top to
bottom, … the further expropriation of private proprietors, takes a new
form. That which is now to be expropriated is no longer the laborer
working for himself, but the capitalist exploiting many laborers. This
expropriation is accomplished by the action of the immanent laws of
capitalistic production itself, by the centralization of capital. One
capitalist always kills many… Along with the constantly diminishing number
of the magnates of capital, who usurp and monopolize all advantages of
this process of transformation, grows the mass of misery, oppression,
slavery, degradation, exploitation; but with this too grows the revolt of
the working-class, a class always increasing in numbers, and disciplined,
united, organized by the very mechanism of the process of capitalist
production itself. The monopoly of capital becomes a fetter upon the mode
of production… Centralization of the means of production and socialization
of labor at last reach a point where they become incompatible with their
capitalist integument. Thus integument is burst asunder. The knell of
capitalist private property sounds. The expropriators are expropriated. .
.

The proletariat seizes the public
power, and by means of this transforms the socialized means of production,
slipping from the hands of the bourgeoisie, into public property. . . .
Socialized production upon a predetermined plan becomes henceforth
possible. The development of production makes the existence of different
classes of society thenceforth an anachronism. In proportion as anarchy in
social production vanishes, the political authority of the State dies out.
Man, at last the master of his own form of social organization, becomes at
the same time the lord over Nature, his own master — free.

(Karl Marx speech delivered to The First
International Working Men's Association on September 8, 1872, in
Amsterdam, Reader, 523,
http://csf.colorado.edu/mirrors/marxists.org/archive/marx/works/1864iwma/1872-d.htm)

Someday the worker must seize
political power in order to build up the new organization of labor; he
must overthrow the old politics which sustain the old institutions, if he
is not to lose Heaven on Earth, like the old Christians who neglected and
despised politics.

But we have not asserted that the
ways to achieve that goal are everywhere the same.

You know that the institutions,
mores, and traditions of various countries must be taken into
consideration, and we do not deny that there are countries -- such as
America, England, and if I were more familiar with your institutions, I
would perhaps also add Holland -- where the workers can attain their goal
by peaceful means. This being the case, we must also recognize the fact
that in most countries on the Continent the lever of our revolution must
be force; it is force to which we must someday appeal in order to erect
the rule of labor.